Question : Cisco 3750 switch error

I have a Cisco 3750 switch with 12 SFP ports.

One of them, that was working just fine until that moment, started to fail. I changed the fiber cable to another port and it worked perfectly. I found the port in the following state:



GigabitEthernet1/0/6 is down, line protocol is down (err-disabled)
  Hardware is Gigabit Ethernet, address is 0019.5516.9406 (bia 0019.5516.9406)
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Auto-duplex, Auto-speed, link type is auto, media type is Not Present
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 2d18h, output 2d18h, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec


I  did:

no shutdown
shutdown

to put it back on, and now it is. But i would like to know what could have happened. Hardware error?

Thanks

Answer : Cisco 3750 switch error

IF a Gbic is falty and flooding the network with errors. OR a interface is flipping between spanning tree states becasue of a incorrectly configered switch on the net work . or amny other error states that may casue big performance hits on the network. a CAT 3500 switch is set by defult to shut down the port and mark it as err disabled.
You can change what errors will casue thsi state and also set a time out for auto recovery (howerver if the fault is serious enough to disable the port i'm not sure i would suggest setting this.

By defult it will not auto recover and is enabled for the full list that Jfredrick posted. IF you havent restarted the switch then your logs will still be on it and you should be able to look at them with a show log (logging) command and see what one of these set it off. however logs are held in open memory and not the NVram. so rebooting a switch will wipe them. as will a memmory error or any thing that causes the switch to crash. you can easly set the switch to log to a remote server.log on to switch go to enable mode and type  config t >> logging and look though the settigns to see how to do it. this also has the benifit of keeping all your switch logs togather

i would also suggest you set
"switch name(config)#service timestamps log datetime msec"  and make sure you switchs are set to the right time. this will make logging entries have the date and time stamped on them to the millisecond, rather than just the switch uptime.(msec is only worth having is you use something like NTP to keep the switches exactly in time with eachother).  
Having it like this makes tracking a error through the net work much simpler. as you can easly see if errors are happening on multiply switches at the same time

also be aware if there is a cisco switch at both ends of the fibre you may get both interfaces at either end err disabled so make sure you check both switches! reenabeling one switch port may make that switch look ok. but if the other end is disabled, then you will still have no data running accross the link.

hope some of that help you, Let us know how it goes

Aaron